Surgical reconstruction of bone defects resulting from resection, severe trauma, or congenital defects has become increasingly common. Reconstructive techniques have involved the use of solid bone grafts. However, solid bone grafts may require extensive surgery, are difficult to contour, and are subject to stress fractures.
Another technique involves osteogenesis with fresh cancellous bone chips and marrow as an amorphous particulate graft. Because successful particulate bone grafting depends on adequate stability, metal trays (titanium chrome cobalt alloys, or stainless steel mesh) have been used to provide fixation and form for the particles. Metal trays are somewhat unsatisfactory, however, as they cannot be readily adapted to achieve optimum fit or contour at the operating table.
For osseous reconstructions which include replacing a condyle, using a metallic bone induction tray, a metallic simulated condyle is affixed to the tray by screws or pins or wire. This usage is subject to the disadvantages of metal fatigue, difficulty of contour modification, and separation of the condyle from the tray proper.
In order to obviate some of the difficulties encountered in the use of metal trays, Leake et al, in 1972, developed an implant tray fabricated of Dacron.RTM..sup.1 and a urethane plastic, e.g., polyether urethane (U.S. Pat. No. 3,849,805, issued Nov. 26, 1974). This non-metallic tray can be fabricated very easily and in a variety of configurations, is very flexible and can be easily altered at the operating table with scissors or scalpel. The flexibility and ease of use of this non-metallic tray indicate its preferability over metal trays. FNT .sup.1 Dacron is a registered trademark of E. I. DuPont de Nemours for its brand of polyethylene terephthalate.
The Leake tray, however, is not conveniently utilized for reconstruction when the bone to be reconstructed is needed for articulation, and the condyle of the patient is not available due to severe trauma, terminal resection or congenital defect. Previously, with osseous reconstruction including the condyle using the Leake tray, a strut of solid bone has been placed in the trough and fixed in place by metal pins or screws, and serves as a condyle. The use of solid bone for this purpose has the same disadvantages as the use of any other solid bone graft, i.e., irregular remodelling, difficulty in contouring, and subjectivity to stress fractures. inadequate, the need for a novel device which would permit the condyle to be reconstructed following a terminal resection has long existed.
As will be seen, the proposed invention has numerous advantages over the bone induction/condylar reconstruction trays used in the past. The device is a prosthetic condyle, formed from a biocompatible plastic, which is integrally affixed to a non-metallic bone induction tray. This device eliminates the need to use any solid bone grafts or metallic prostheses in the reconstructive process. Additionally, fabrication on standard molds may be readily carried out, with contouring and customizing of the tray/condyle combination readily accomplished at the operating table. The invention expands the use of existing non-metallic bone induction trays where the patient's condyle is not available or not usable.